The invention relates to a color display device comprising a color cathode ray tube including an in-line electron gun for generating three electron beams, a color selection electrode and a phosphor screen on an inner surface of a display window and a means for deflecting the electron beams across the color selection electrode.
Such display devices are known.
The aim is to make the outer surface of the display window flatter, so that the image represented by the color display device is perceived by the viewer as being flat. However, an increase of the radius of curvature of the outer surface will lead to an increase of a number of problems. The radius of curvature of the inner surface of the display window and of the color selection electrode should also increase, and, as the color selection electrode becomes flatter, the strength of the color selection electrode decreases and hence the sensitivity to doming, vibrations and droptest increases. An alternative solution to this problem would be to curve the inner surface of the display window more strongly than the outer surface. By virtue thereof, a shadow mask having a relatively small radius of curvature can be used. As a result, doming and vibration problems are reduced, however, other problems occur instead. The thickness of the display window is much smaller in the centre than at the edges. As a result, the weight of the display window increases and the luminosity of the image decreases substantially towards the edges.